We’ve been integrating our social media campaigns for our web marketing clients for quite awhile as both social media tactics, but also as a way to improve SEO. Our tactics include blogs and social media accounts, both official and not, but this article does a good job of showing the impact of making sure you are using social media effectively for SEO.
Search Engine Land’s Danny Sullivan asked the engines what social signals they consider in their algorithms in December 2010. He found that with social and search company relationships and partnerships changing all the time (like the Twitter and Google, Bing and Facebook, etc.) we can assume that no matter how the details of the social signals above may change, the search engines are taking a hint from social activity in determining which sites people are finding valuable, and likely using those hints to help drive site and page rankings.
Consider how and where you’re encouraging your site visitors to use Facebook Likes, tweet your content, and share it by other means (emailing, copying and pasting a link, other social networks, etc.). Make sure your tweets contain relevant keywords, use hashtags for primary topics, be sure to include a link back to your page, tweet hot topics when it’s relevant, and optimize your titles and descriptions using open graph protocol for your Facebook Likes.
via 3 Ways Social Media Can Affect Organic Search Performance | Yahoo! Advertising Blog.